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This paper presents a theoretical study of the thermally driven behavior of a shape memory alloy (SMA)/FGM actuator under arbitrary loading and boundary conditions by developing an integrated mathematical model. The model studied is established on the geometric parameters of the three-dimensional laminated composite box beam as an actuator that consists of a functionally graded core integrated with SMA actuator layers with a uniform rectangular cross section. The constitutive equation and linear phase transformation kinetics relations of SMA layers based on Tanaka and Nagaki model are coupled with the governing equation of the actuator to predict the stress history and to model the thermo-mechanical behavior of the smart shape memory alloy/FGM beam. Based on the classical laminated beam theory, the explicit solution to the structural response of the structure, including axial and lateral deflections of the structure, is investigated. As an example, a cantilever box beam subjected to a transverse concentrated load is solved numerically. It is found that the changes in the actuator's responses during the phase transformation due to the strain recovery are significant.

This work investigates the free vibration and buckling of a two-layered cylindrical shell structure made of an elastic embedded functionally graded (FG) shell subjected to combined static and periodic axial forces. Such structures are widely used in chemical and nuclear reactors, space and aerial industries, and so on. Material properties of an FG cylindrical shell are considered to be temperature dependent and graded in the thickness direction according to a power-law distribution in terms of the volume fractions of the constituents. Theoretical formulations are presented based on two different methods of the first-order shear deformation theory considering the transverse shear strains and the rotary inertias and the classical shell theory. The results obtained show that the effect of transverse shear and rotary inertias on free vibration of an FG cylindrical shell is dependent on the material composition, deformation mode, and geometry parameters of the shells. It is concluded that the application of an outer elastic layer increases elastic stability.

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In this study, strength behavior and crack-formation mechanism of E-glass fiber exposed to sulfuric acid environment for different immersion times were investigated. In order to study the strength degradation, E-glass fibers were immersed in sulfuric acid. Strength reduction, stiffness, and fracture strain of fibers vs. immersion times were studied. The corrosion mechanism of E-glass fiber exposed to acid, were examined by quantitative X-ray fluorescence method. The results showed that corrosion of E-glass fiber was accompanied by removal of Al, Ca, and Fe ions from the fibers. Moreover, intact and degraded fibers were examined by scanning electron microscope and energy dispersive X-ray (EDX) microanalysis methods to show the relation between the reaction of E-glass fiber elements and acid environment. The ion-depletion-depth model was used to study the fracture process. The results showed that by increasing the immersion time in acid, spiral stress induced due to the shrinkage of E-glass fiber surface caused axial cracks in fibers. Different points of fibers, in which cracks were generated, were examined by EDX method. The results were used to explain the role of Al, Ca, and Fe ions in creation of surface cracks on E-glass fibers subjected to sulfuric acid for different immersion times.